Keep Quiet
by ColieMacKenzie
Summary: An undercover op causes Castle and Beckett some unexpected frustration. AU, set early season 5


**Keep Quiet**

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 _An undercover op causes Castle and Beckett some unexpected frustration. AU, set early season 5; light on any kind of plot. Thank you to dave_ck for the prompt!_

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This. Was. Torture. Cruel and unusual punishment. He wasn't sure what he'd done to deserve this, but he was convinced he was not going to survive this week.

He adjusted the vases on the sideboard that he'd already moved a quarter of an inch to the left a minute ago, rearranged a flowering stem here and there in the large bouquet as if he knew what he was doing. He was fidgety, didn't know what to do with his hands. His skin was humming with the constant thrum of desire beneath his skin.

Castle turned around in the open concept living space of the gorgeous brownstone. Everything was ready for the small sales party they were hosting in about a half an hour, the decorative bowls and flowers staged, wine glasses set out and bottles chilling in the cooler, the platters of hors d'oeuvres arranged on the large kitchen counter. He sighed, failed to drum up any excitement for the rest of their mission.

Undercover. He snorted in disbelief. He would've given an arm and a leg if someone had told him at any time in the last four years that he would get to go undercover with Beckett pretending to be a couple, playing house. To be allowed to smile at her freely, let his affection for her shine through that he had to keep so carefully hidden. To get to touch her hand, lace his fingers with hers, and rest his palm across her lower back in innocent couple-y gestures. To tease her, play with her, draw her from her shell a little bit. The excitement and danger of it, the sexual tension that had always simmered and crackled between them just below the surface, ready to combust at any minute, had made the prospect of an undercover mission seem like an alluring adventure.

Well, the joke was on him.

Now he knew what she looked like stark-naked underneath him, his name on her lips, her eyes liquid amber and her cheeks flushed with pleasure, as much as he was acquainted with sleepy, morning-tousled Beckett, her hair an adorable mess of curls and her skin still warm with sleep. He knew the taste of her kisses, and the feel of her skin beneath his fingertips, smooth like silk and sensitive to every touch. And in a cruel twist of fate, he didn't get to have her.

They were undercover - how Gates had even gone for this was beyond him - playing a couple in a fancy, staged New York City brownstone. A real estate scheme had led to a string of murders, and it was on them to lure out their suspect. Like he had fantasized so often in the past, he got to hold her hand in public, look at her adoringly, press tender kisses to her lips.

But alone in the house, sharing the kitchen and living spaces, the spacious bathroom and the sinfully comfortable California King bed, he had to keep himself away, remain at a 'professional' distance. He couldn't touch her, kiss her, love her. Because in order to catch their suspect in the act, the entire house was under surveillance. Every single room was equipped with at least one camera, and microphones, and her colleagues - Ryan and Esposito and the team of Detectives on this op, even Captain Gates for crying out lout - able to see and hear every single interaction between them.

And no one could find out about their relationship. It had been their secret for months, ever since Kate came back to the Precinct after her suspension. It'd been fun, for a while, to keep it hidden. Clandestine meetings in the stairwell for drawn-out kisses and rushed make-out sessions; secret handshakes and inside jokes, and shared smiles when no one was looking. It'd been such a wonderful secret to share with her, sexy and playful and special.

But he's never wished for everyone else to know more than during the days since the start of their undercover op. So that after each day spent schmoozing rich, obnoxious real estate clients, he could roll his girlfriend underneath him in that gigantic bed. He ached to kiss her thoroughly, and peel the clothing off her body piece by piece to reveal her gorgeous skin, trace his lips along every peak and plane and valley. To press his mouth between her legs and taste her, rich and tart. He yearned to feel her squirm against him, lost in sensation when he touched her, filled her, loved her hard and fast or slow and deliberate, her heart pounding and her voice breathless and the sounds she made a melody he wanted to hear for the rest of his life. It was killing him; the tension so thick between them that you could cut it with a knife. She was near him twenty-four seven and he missed her so much that he ached with it, his arousal perpetually churning in his gut, and his body strung tight with tension in every muscle.

He fervently hoped that this party would draw their suspect out enough to garner the evidence they needed so that they could get out of here and go home. Realistically though, he suspected they'd be stuck here another three days at least, and he was going to die from not getting to kiss her properly.

He jogged up the flight of stairs to the upper floor; he still needed to put on his suit, and he hadn't seen Kate in a while.

"Kate?" He strode through the bedroom and toward the bathroom, didn't see her in either space.

"In here," her voice called from the walk-in closet. He turned for their shared closet, stepped inside, froze to the spot with his heart pounding and want churning low in his body. Kate was flipping through the few clothes she had brought and hung up on the rack; naked except for the black lace bra and tiny matching panties, and a pair of black, five-inch pumps that made her toned legs look endless. He swallowed hard. Her skin was so soft, looked like silk in the dim light of the closet. His eyes tracked from her flat stomach to her breasts swelling above the cups of her bra, the soft waves of her hair tumbling down her back, her elegant neck and those sharp, enticing cheekbones.

"You're killing me, Kate," he ground out, his breathing labored. He dug his nails into his palms, his fingers twitching to touch her.

"Shhhh." She glared at him, leaned around him to close the closet door behind them. Her body brushed against his as she moved, and need arrowed through his midsection, hardened his length that strained against the constraints of his pants. Kate stilled, looking up at him with those wide eyes. Her lips fell open; her blood was throbbing through the vein in her neck. The closet enfolded them within the silence of its four walls, muffling all sound and emphasizing the labored rhythm of their combined breathing.

"You know," Kate whispered, her voice raspy in that sensuous way that set him aflame. "I think this is the only space in this whole house with no cameras."

He stared at her, a second ticking by, two, three, his heart pounding against his ribs, the rush of blood in his ears, every cell of his body _aware_ of her, her scent and her warmth and the rush of her breath. Her chest rose and fell as her breathing sped up, lifting the tops of her breasts alluringly over the edge of her bra, and he grabbed her waist, pushed her into the wall of the closet. Kate sought his mouth with a moan that trembled from his lips straight down to his midsection, her tongue curling inside his mouth with a hunger that matched his.

Castle ran a hand along her lower back to the curve of her ass, down the length of her thigh and the back of her knee, lifting her leg high over his hip to fit himself into the vee of her thighs. The damp heat of her bloomed through her thin underwear and she rolled her hips against him. His body strained, his hips thrusting, pressing, seeking, and she dug her fingernails into his neck, guiding the angle of his head for a deepened kiss.

"I need you to touch me," she groaned against his mouth, bit his bottom lip and soothed the sting with her tongue. "Now."

He dropped to his knees before her, fingers hooked around the thin lace waistband of her panties. He dragged the underwear down her legs and she stepped out of them, widened the stance of her legs. Face-level with her sex, he buried his face against her, inhaling her scent, his fingers gripping the taut cheeks of her ass. Her nails were scoring his scalp, her hips undulating against him and the scent of her arousal strengthened. He knew what she would feel like against his fingertips, wet and slippery and swollen, could practically taste her against his tongue. He looked up at her and Kate unclipped the front fastener of her bra, let the cups fall open, the garment dangling off her shoulders. Her breasts freed to his gaze, the proud peaks and the pink nipples hardened with arousal. He reached up, flicked his thumb across one nipple. She cried out.

"Shhhh," he soothed in whispered tones, worried how sensitive the microphones in the bedroom would be, how much they might pick up through the closed door of the closet.

"Gotta be quiet, Kate." He was speaking against the low of her stomach, his lips grazing the tender skin just above her sex and she was shivering, her hips pushing into him.

"Don't know if I can." She gasped the words, her eyes slow to open as she looked down at him, her pupils blown with arousal. "You drive me fucking wild."

He grinned a lazy grin. It was just so hot when she swore, when he could drive her to the point where she could let herself go, wild and unconstrained and free. His body was straining against his pants, the blood pounding hard and fast through his veins.

"What drives you wild, Beckett?" Castle ran his fingertips up over the cheek of her ass, scraping with his nails, the fingers of his other hand teasing her nipple, drawing circles around her breast. "What do you want me to do to you?"

"Su-" She had a hard time gasping in a breath. "Suck my-" she whispered, straining to keep her voice low. "My breasts."

He rose before her, framed both of her breasts with his hands, watching her face as he did. He loved how she filled his palms just right, the heat of her flesh, the heaviness when she was aroused. He kneaded them, watched her back arch off the wall, and then he wrapped his mouth around one nipple, sucking hard, tweaking the other with his fingertips. She strained to suppress the sounds that he drew from her throat, her body shivering and arching into him. Castle rolled his tongue around her nipple, filled his mouth with her.

"You are the sexiest woman I've ever seen," he mumbled the words around her breast in his mouth, felt the vibrations of her moan reverberate in her chest. She liked to hear his voice during sex, squirming when he whispered sweet nothings and dirty thoughts against her skin. He switched sides, his lips wrapped around the nipple of her other breast, rolling the hard nub against the roof of his mouth.

"More," she ground out, fingers clinging to his shoulder. He sucked harder, let his hand trail down over her lattice of her ribs, the line of her abs. He traced her navel, and her muscles tightened in her abdomen, her hips shifting. His fingers trailed lower, slid between the lips of her sex. She was wet against his fingertips, her clit swollen and slippery, her body open for him and he groaned, pressing the sound around the flesh of her breast. He circled her clit, teasing lower to her entrance, then back to her clit, lifting his mouth from her breast to find her mouth.

"What else?" He murmured the question against her lips, nipping the tender flesh with his teeth. "What else do you want, Beckett?" This was something else he learned early on - she got off on it when he called her Beckett in bed, with his voice turned low and the consonants sharpened.

"Your mouth on me," she said, kissing him, her tongue deep and hard in his mouth. "Suck on me, Rick."

He dropped to his knees before her. The rough carpet fibers ground against his kneecaps. "Open your legs, baby," he urged her, looking up at her from his position of worship on the floor before her. Her eyes came open, meeting his, her irises turned to amber, her pupils large. She looked at him with that unique combination of lust and adoration and such profound trust that his heart skipped a beat before it resumed its racing rhythm, throbbing harshly in his throat and in his fingertips, his stomach and his hard length.

She held his gaze and widened her stance, revealing herself to his eyes, pink swollen flesh and glistening wetness. Her pulse was throbbing through the tender vein in her neck, and her muscles quivered in her stomach and her legs. Castle braced his hands around her thighs, watching her, aware of the delicious anticipation between them, desire sparking like electricity. It'd been months since that first rain soaked night in May and none of the fire between them had calmed; quite the opposite. Each time with her seemed to stoke it further, the flames licking higher, consuming everything in their path and he sometimes wondered whether they would reach a point where they would simply combust.

"Castle!" She barked tonelessly, trying to give her voice bite while staying quiet, and he might have laughed at her order if his mouth wasn't already buried between her legs. He curled his tongue through her folds, stroked a long line that ended at her clit, rolling the tip of his tongue around the swollen nub. Her arousal was sweet in his mouth, the taste of tart cherry so much her that he could've wept with it. He sucked her between his lips, felt the strain of her body, the way her muscles quivered, breath held as she tried to suppress the moans rising from her.

She was loud, usually, unconstrained in her needs, and he loved how she had never held back with him. Once she had come to him, she had given herself completely, as if freed from a heavy weight. Yet this quiet encounter - their heavy breathing and the wet noise of his mouth against her the only sounds in the muffled space - the way she struggled to keep herself quiet, was deliriously hot.

With her fingers gripped around strands of his hair, she directed his head where she wanted him, when she wanted more pressure or less, and he teased her clit, stroked patterns with his tongue, delving shallowly against her entrance. Kate tilted her hips, undulating, seeking to fit herself more fully against his mouth and he chased her flavor, teased and sucked and nipped.

"Harder," she ordered when he suckled on her clit, so he sealed his lips around her, tucking her fully into his mouth, flicking the tip of his tongue over the hard nub. She shifted in his hands, her muscles quivering, and he tightened his grip around her hips to hold her in place. Her nails dug into his scalp, short sharp sounds escaping her throat that she couldn't quite suppress. He knew she was close, could feel it in the shiver of her body, taste it against his tongue. He drew from her and her thighs clamped closed around his head, every muscle taut, in her abdomen, her back, her legs. Her flavor flooded his mouth as she came. Kate jerked into him, muscles tightening, releasing, tightening again; her knees buckled and he had to grip her waist and hip, hold her up through the quivers of her orgasm until she slumped bonelessly against him, his head still cradled to her stomach and her body folded around him. She was breathing hard, trying to draw air into her lungs, her fingers sifting through his hair.

Castle drew her with him to the floor and she arranged herself over his lap, folded her arms around his shoulders. Her sex slid over his length that strained underneath his pants, the wet heat of her seeping through the fabric. She rolled her hips against him, sought his mouth for a slow, deep, tender kiss that belied the dirty rhythm she was dancing over his lap. He let his fingers roam across her back, tracing the nobs of her spine, the soft planes of her skin, the play of muscles beneath. He adored her, all her contradictions, soft and hard, dirty and sweet and loving.

Kate let her fingers trail down his chest, and before he was aware of the movement, she had tunneled under the waistband of his pants, wrapped her fingers around his length. He groaned, the raw noise drawn from deep inside him, unstoppable as it forced its way out.

"Shhhh," she scolded. "Gotta be quiet Castle." Her teeth dug into her bottom lip while she played with him, her fingers tender around his length, her touch hot. She circled the head, thumb grazing over the tip in a way that he was afraid might make him combust before he was inside of her.

"Think _you_ can be quiet, Rick?" She teased, voicelessly popped the consonants of his name. "Keep your mouth shut?" He whimpered, pressed a hard kiss to her mouth to hide the sound. "Can you be inside me and not make a sound?"

He gripped her wrist, stilling her hand. "Turn around," he ground out, eyes squeezed shut to regain a modicum of control.

Kate climbed off his lap and he opened his eyes to watch her settled on her hands and knees in front of him. She arched her back, the gorgeous curves of her ass presented to him like a gift, and need speared through him like arrows made of pure fire, his body taut with it, his mouth parched. She looked back at him over her shoulder, snuck a hand between her legs and played her fingers over her clit, her eyes rolling back as she did. The vision was so hot he feared he might come right then and there.

"I need you inside." Her voice was raw, rung with the same fiery, desperate yearning that was thrumming through him. He tore his pants down to his knees, grabbed her hips in his hands, lined himself up and drove home.

They stilled. He bit at the animalistic roar that pushed from within him, felt it stuck in his throat. She clenched around him, the shiver of her muscles milking him and she felt so amazing around him, warm and wet and welcoming.

Kate rolled her hips against him, seeking, needing, quivering, her breathing labored. He pulled out, thrust back in to the hilt. She quaked at the intrusion, her body blooming open around him and he knew he would never get enough of this, he could never have enough of her, she was everything. He thrust into her warmth, moving faster in rhythm with the undulations of her body. She dropped her head, exposing the smooth column of her neck, her hair sweeping the floor. He reached around for her breasts, kneading the flesh. Her body tensed, her whimpers shivering through him. He needed her closer, ached for her skin against his. Wrapping an arm around her stomach he drew her up and against him. She straightened like a goddess over his lap, her back plastered to his chest, an arm hooked around his neck and her cheek pressed to his. It made her tighter around his length, changed the angle of his thrusts and they both moaned, the sound too loud in the complete silence surrounding them.

He buried his mouth to her shoulder to muffle his voice, pressed a hand over her mouth to muffle hers. It seemed to spiral her higher, this reminder of their secret tryst, the demand to be quiet. Her mouth opened over his palm, teeth grazing his flesh, and his other hand trailed low on her abdomen, his fingers sliding across her clit. She groaned into the flesh of his palm, bit him, and he rubbed her harder, thrusting up into her, chasing the undulations of her hips. It was fast then, their flesh slapping together loud enough he wondered in passing if this would be the sound that could be heard through the microphones. But all thought wiped from his brain when he slammed into her and she squeezed around him, riding him hard until the wet warmth of her clamped tight around him, so swollen with arousal that he could barely move inside her. Her abs tensed, thighs squeezing as she broke apart over him in a harsh rapid explosion of her body. Her muscles quivered, her body jolting around his, lungs left breathless, soundless while she milked his length. Her orgasm carried him with her, white hot oblivion claiming him, wiping him blank, his body jerking, shaking into hers until he collapsed over her, utterly spent.

It took long minutes for his breathing to even out, for any clear thought to reenter his brain.

"Holy shit," he ground into her shoulder, voice muffled by her skin. "We should go undercover more often."

She groaned on a laugh. "Oh god. We have to get dressed." Still she didn't move.

"I missed the feel of you," he admitted into her skin. Kate turned in his embrace, her eyes meeting his. She framed his face with her palms to draw him closer, and held his gaze as she kissed him, a sweet and languid, deliberate kiss. And even though she was silent, he knew every word she didn't yet say.

Then they untangled their limbs from each other, hurried to get dressed. He couldn't wait to get to go home.

With her.


End file.
